Siemens does not give feedback to complaints

I bought two hearing aids from an Audioligist in Durban. They are expensive waterproof aids as I am exposed to wet conditions and excessive perspiration in hot climates.<br> The first one bought was faulty from the start with strange noises and excessive feedback whistling.<br> The audiologist said it was new and would settle down but it remained noisy. The second one is perfect and makes no noises and I can hear properly. I went back to the audiologist and complained again and she sent both hearing aids for service and check up for the noise. When they returned the one was still faulty.<br> It was returned to Siemens and they sent it back saying they had changed the unit but the symptoms were still exactly the same.<br> I have sent two complaint emails to Siemens and the first one was ignored and the second one with a reply of sending it to the correct department. <br> So I sit with a hearing aid I cannot use and still have to ask people to repeat themselves.<br> I am going on a holiday and would like two functioning hearing aids but it seems unlikely with the poor response from Siemens.